Aquariums, I always found cool (obviously)... Turning a piece of furniture like a table, coffee table, a toilet, old TV, etc. into an aquarium, not so cool .. lol
Love the boardroom one. It's actually elevated off the ground so you can siphon the dern thing, and it would definitely be really interesting with some water lillies and fish that look good from above... Wouldn't very much like to have meetings under MH lighting though...